The present invention relates to a modulation doped field effect transistor. More specifically, the present invention relates to a modulation doped field effect transistor composed of a silicon substrate on which a modulation doped silicon-germanium/silicon layer sequence has been applied, and at least one control electrode.
Such a transistor is also called a MODFET and is disclosed in the article by T. P. Pearsall et al, "Ge.sub.x Si.sub.1-x Modulation Doped p-Channel Field Effect Transistor", pages 400-405, Proc. 1st Intern. Symp. on Silicon MBE, Vol. 85-7, May, 1985, Toronto, Canada; Ed. J. C. Bean, Electrochemical Society, Pennington, N.J.
The MODFET disclosed there includes a sequence of semiconductor layers based on silicon (Si) which permits the construction of a MODFET having a so-called p-conductive channel. However, most circuit applications require field effect transistors (FET's) which have an n-conductive channel.